Cracking

Chemistry: AQA GCSE Higher, topic 7.1.10

Cracking

Cracking is the process that breaks down long-chain hydrocarbons into shorter-chain molecules that are more useful. Cracking is an example of a thermal decomposition reaction. Cracking can be done in two ways:

Catalytic cracking

Vapourised heavy hydrocarbons are passed over the top of a heated catalyst.
Alkanes and alkenes are produced by this reaction.
E.g. hexane → butane + ethene

Steam cracking

Vapourised heavy hydrocarbons are combined with steam in a high temperature environment.
Alkanes and alkenes are produced by this reaction.
E.g. decane → octane + ethene

Test yourself on Cracking

Examples of cracking reactions
What type of chemical reaction is cracking?
In the reaction hexane → butane + ethene, what type of hydrocarbon is ethene?
What are the products of cracking?
What do catalytic cracking and steam cracking have in common?

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